Sugar accumulation during enzyme hydrolysis and fermentation of cellulose

An alternative microbial approach to cellulose degradation utilizing Costridium thermocellum, a thermophilic and obligately anaerobic bacterium, was investigated. This organism rapidly hydrolyzes cellulosic materials, including crystalline and non-delignified substrates. C. thermocellum produces mainly extracellular cellulase enzymes, though additional enzymes can be released from residual solids. An intriguing aspect of the C. thermocellum fermentations on cellulose is the accumulation of soluble sugars. Preliminary chromotog. analyses reveal that glucose and cellobiose appears to be insensitive to the accumulating sugars. Taken together, these observations suggest that direct conversion of cellulose to soluble sugars by C. thermocellum may indeed be a feasible microbial route to the utilization of cellulosic biomass.